This application is a request for a Mentored Patient-Oriented Research Career Development Award (K23) from the NIMH to foster the academic career development of the applicant, Donna B. Pincus, Ph.D. The applicant will work closely with her primary mentor, Dr. David Barlow, and co-mentors, Dr. Sheila Eyberg, Dr. Thomas Ollendick, Dr. Anne Marie Albano, and Dr. Simon Budman, to develop expertise in conducting clinical research to establish innovative and efficacious interventions for young children with anxiety disorders. In a career development plan spanning five years, the applicant has delineated specific short-term and long-term goals to prepare her for a patient-oriented research career. Short term goals include obtaining additional didactic training and mentoring in several "core" areas that have been chosen to deepen her existing skills as well as expand her skills into new areas. The applicant's long term goals are to develop a programmatic line of research that is focused on developing efficacious, innovative treatments for childhood anxiety disorders, and to launch a highly productive research career as a clinical scientist. A formal research plan is proposed to investigate the most prevalent, yet most under-researched anxiety disorder in childhood: Separation Anxiety Disorder (SAD). Despite growing evidence that SAD is prevalent in young children and linked to later psychopathology, there have been few treatment studies investigating the efficacy of interventions for SAD; those that do exist typically have not included young children. Recent experimental evidence highlights the potential clinical utility of incorporating parents more centrally in the treatment of childhood anxiety disorders. The primary goal of the proposed research plan is to apply an existing, empirically supported parent training intervention (Parent-Child Interaction Therapy; PCIT) to the treatment of children ages 4-8 with SAD. Although originally designed as a treatment of oppositional children, PCIT incorporates each of the skills anxiety researchers have indicated as essential training components for reducing child anxiety, and thus, is expected to be effective in reducing children's separation fearful behaviors and in promoting improved parent-child interactions. The specific goals of this project are: (1) to evaluate the efficacy of PCIT for reducing separation anxious behaviors in young children (2) to assess long term maintenance of change at 3, 6, and 12 months following treatment (3) to investigate potential mechanisms of improvement. This research project will be the first controlled clinical trial that has been conducted with very young children with separation anxiety, and thus, will begin to fill in a significant gap in our knowledge of this at-risk population. This project will provide the applicant with a solid foundation of skills for the continued development of innovative, empirically validated interventions for children with anxiety disorders and their families.